First of all, spaghetti squash is definitely delicious.
Secondly, in what sense do you mean 'bad for you'?
Assuming that you are asking in relation to weight maintenance, 'too much' is only relevant to how the rest of your diet looks.
If you are tracking your calories, then determining how much is 'too much' should be self evident. Do you track?
However, it is tough to comment if you are not tracking. I suppose that if you feel that you are gaining weight or losing weight or whatever is the opposite of what your current goal is, then you may need to cut back on/ keep piling up the spaghetti squash.